Open Loop Microphone Test

This sequence demonstrates the two most common microphone measurements, frequency response and sensitivity, on a microphone embedded in a recording device. Typically when measuring a microphone the response of the device can be captured simultaneously with the stimulus. However, with devices such as voice recorders and wireless telephones forming a closed loop can be cumbersome or impossible. This sequence demonstrates how to measure such a device by recording the signal on the device under test, transferring that recording to the computer running SoundCheck and then using a Recall step to import the recorded waveform and analyze it.

The sequence operates by prompting the operator to begin recording on the device under test and then a stepped sine sweep is generated from 10 kHz to 100 Hz through a source that has previously been calibrated to produce 1 Pascal across the frequency band. The operator is then prompted to transfer the recording to the computer and then to load the file in to SoundCheck via a Recall sequence step. At this point the sequence displays the recorded waveform and prompts the operator to enter the start time of the actual stimulus signal: